A method of transmitting a data signal using an optical transmitter of an optical communications system. A first encoder processes an N-bit input vector in accordance with a first mapping to generate a corresponding M-bit data stream. A Forward Error Correction encoder processes the M-bit data stream in accordance with a predetermined FEC encoding scheme to generate an encoded signal. A constellation mapper maps the encoded signal to symbol values in accordance with a predetermined modulation scheme to generate a corresponding symbol stream. A modulator modulates a carrier light in accordance with the encoded symbol stream to generate an optical signal for transmission through the optical communications system. The first mapping can be adjusted to maximize performance of the optical communications system.
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1. A method of transmitting a data signal using an optical transmitter of an optical communications system, the method comprising: processing an N-bit input vector in accordance with a first mapping to generate a corresponding M-bit data stream, wherein N≦M; processing the M-bit data stream in accordance with a predetermined Forward Error Correction (FEC) encoding scheme to generate an encoded signal; mapping the encoded signal to symbol values in accordance with a modulation scheme to generate a corresponding symbol stream; and a modulator of the optical transmitter modulating a carrier light in accordance with the symbol stream to generate an optical signal for transmission through the optical communications system, wherein the first mapping comprises a tree code implemented by a plurality of nodes arranged in layers, each node having an input connected to receive a signal from a node in a previous layer and at least two outputs, the nodes of each layer being further configured to receive a respective bit of the N-bit input vector and implement a memoryless logical operation which divides the signal received via its input between each of its outputs based on the value of the received bit of the N-bit input vector.
A method for transmitting data using an optical transmitter. An N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a special mapping. This mapping uses a tree code with nodes arranged in layers. Each node receives input from the previous layer and has at least two outputs. Nodes receive a bit from the N-bit input vector and perform a logical operation. This operation divides the input signal based on the bit's value. The M-bit data stream is then encoded using Forward Error Correction (FEC). The resulting encoded signal is mapped to symbols based on a modulation scheme. Finally, the transmitter modulates a light carrier with the symbol stream to create the optical signal for transmission.
2. The method of claim 1 , wherein the modulation scheme is configured to map syndrome bits of the encoded signal to sign bits of the symbol stream.
In the optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission, the modulation scheme maps syndrome bits (error correction information) from the encoded signal to the sign bits of the generated symbols. This helps optimize error correction during signal reconstruction.
3. The method of claim 1 , wherein the first mapping is adjustable to tune any one or more of: a noise tolerance; a non-linear tolerance; a spectral efficiency; and a system margin.
In the optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission, the initial mapping process (N-bit to M-bit) is adjustable. This allows fine-tuning of noise tolerance, non-linear tolerance, spectral efficiency (data rate), and overall system margin (performance headroom) to optimize the optical communication system.
4. The method of claim 1 , further comprising: a controller of the optical transmitter receiving a parameter indicative of a data transmission performance of the optical communications system and adjusting the first mapping to tune the data transmission performance of the optical communications system, wherein adjusting the first mapping comprises: decreasing the number of data bits per baud of the optical signal if the parameter is greater than a first predetermined threshold; and increasing the number of data bits per baud of the optical signal if the parameter is less than a second predetermined threshold.
In the optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission, a controller monitors data transmission performance. If performance is worse than a threshold, the controller adjusts the initial mapping (N-bit to M-bit) to decrease the data bits per baud. If performance is better than another threshold, it increases the data bits per baud. This dynamic adjustment optimizes data transmission based on real-time conditions.
5. The method of claim 4 , wherein adjusting the first mapping comprises any one or more of: adjusting a number of data bits per baud of the optical signal; adjusting a ratio between N and M; adjusting a number of 0's in the M-bit data stream; and applying respective different probability distributions to at least two bits of each symbol of the symbol stream.
In the adaptive optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission and the initial mapping is adjusted based on performance, the controller adjusts the mapping by changing one or more of the following: the number of data bits per baud, the ratio between N and M (input/output bit counts), the number of zeros in the M-bit data stream, and/or the probability distributions applied to individual bits within each symbol.
6. The method of claim 5 wherein the number of data bits per baud is a rational number p/q, and wherein adjusting a number of data bits per baud comprises adjusting either one or both of p and q.
In the adaptive optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission and the initial mapping is adjusted based on performance by varying the data bits per baud, the number of data bits per baud is expressed as a rational number p/q. Adjusting the data bits per baud involves changing either p, q, or both.
7. The method of claim 6 wherein q>1; and wherein p and q are relatively prime.
In the adaptive optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission and the initial mapping is adjusted based on performance by varying the data bits per baud, and the number of data bits per baud is expressed as a rational number p/q, then q is greater than 1 and p and q are relatively prime (their greatest common divisor is 1). This ensures a fractional number of bits per baud.
8. The method of claim 4 , wherein the parameter comprises any one or more of a bit error rate, a confidence metric, and a buffer fill.
In the adaptive optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission and the initial mapping is adjusted based on performance, the parameter used to indicate data transmission performance is one or more of the following: bit error rate, a confidence metric (signal quality), or buffer fill level (network congestion).
9. The method of claim 4 , wherein the first and second predetermined thresholds are equal.
In the adaptive optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission and the initial mapping is adjusted based on performance, the first threshold (above which data bits per baud are decreased) and the second threshold (below which data bits per baud are increased) are equal.
10. The method of claim 4 , wherein the first predetermined threshold is greater than the second predetermined threshold.
In the adaptive optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission and the initial mapping is adjusted based on performance, the first threshold (above which data bits per baud are decreased) is greater than the second threshold (below which data bits per baud are increased). This creates a hysteresis effect.
11. The method of claim 1 , wherein the modulation scheme is selected to maximize data transmission speed through the optical communications system under optimum conditions.
In the optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission, the modulation scheme used is specifically chosen to maximize the data transmission speed through the optical communication system under optimal conditions.
12. The method of claim 1 , wherein the modulation scheme is selected to decrease a nonlinear interference.
In the optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission, the modulation scheme is selected to minimize non-linear interference within the optical communication system.
13. The method of claim 1 , further comprising: a receiver detecting symbols modulated on the optical signal; a digital signal processor processing the detected symbols in accordance with the predetermined encoding scheme to generate an M-bit data stream; the digital signal processor further processing the M-bit data stream in accordance with the first mapping to recover an N-bit vector corresponding with the N-bit input vector.
In the optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission, a receiver is used to detect the symbols modulated on the optical signal. A digital signal processor (DSP) then decodes the symbols according to the FEC scheme to generate the M-bit data stream. The DSP further processes this M-bit stream using the inverse of the initial mapping (tree code) to recover the original N-bit vector.
14. The method of claim 4 , wherein the first mapping comprises any one or more of a shaping function and a shell coding.
In the adaptive optical transmission method where an N-bit input is converted into an M-bit data stream (where N is less than or equal to M) using a tree code mapping implemented with nodes arranged in layers, then encoded using Forward Error Correction (FEC), and mapped to symbols based on a modulation scheme before modulating a light carrier for transmission and the initial mapping is adjusted based on performance, the initial mapping from N-bits to M-bits utilizes shaping functions and/or shell coding techniques. These techniques are used to optimize the signal constellation for better performance.
15. A receiver for detecting a data signal transmitted through an optical communications system from a transmitter, the receiver comprising: a detector configured to detect symbols modulated on an optical signal; and a digital signal processor configured to process the detected symbols in accordance with a predetermined encoding scheme implemented by the transmitter to generate an M-bit data stream, and for processing the M-bit data stream in accordance with a first mapping implemented by the transmitter to recover an N-bit vector corresponding with the data signal, wherein the first mapping comprises a tree code implemented by a plurality of nodes arranged in layers, each node having an input connected to receive a signal from a node in a previous layer and at least two outputs, the nodes of each layer being further configured to receive a respective bit of the N-bit input vector and implement a memoryless logical operation which divides the signal received via its input between each of its outputs based on the value of the received bit of the N-bit input vector.
An optical receiver detects data transmitted over an optical communication system. It has a detector that receives symbols from the optical signal. A digital signal processor (DSP) processes these symbols. First, it uses the FEC decoding scheme to create an M-bit data stream. Then, it uses the reverse of the initial mapping (N-bit to M-bit) to recover the original N-bit vector. This mapping uses a tree code structure. Each node receives input from the previous layer and has at least two outputs. Nodes also receive bits from the N-bit input and split the signal based on the bit's value.
16. A transmitter for transmitting a data signal in an optical communications system, the transmitter comprising: a first encoder configured to process an N-bit input vector in accordance with a first mapping to generate a corresponding M-bit data stream, wherein N≦M; a second encoder configured to process the M-bit data stream in accordance with a predetermined Forward Error Correction (FEC) encoding scheme to generate an encoded signal; a constellation mapper to map the encoded signal to symbol values in accordance with a modulation scheme to generate a corresponding symbol stream; and a modulator configured to modulate at least two dimensions of a carrier light in accordance with the symbol stream to generate an optical signal for transmission through the optical communications system, wherein the first mapping comprises a tree code implemented by a plurality of nodes arranged in layers, each node having an input connected to receive a signal from a node in a previous layer and at least two outputs, the nodes of each layer being further configured to receive a respective bit of the N-bit input vector and implement a memoryless logical operation which divides the signal received via its input between each of its outputs based on the value of the received bit of the N-bit input vector.
An optical transmitter sends data over an optical communication system. It includes a first encoder that transforms an N-bit input vector into an M-bit data stream (N less than or equal to M) using a specified mapping. This mapping uses a tree code with nodes arranged in layers. Each node receives input from the previous layer and branches to at least two outputs. Nodes receive a bit from the N-bit input and perform a logical operation. A second encoder applies Forward Error Correction (FEC) to the M-bit data stream. A constellation mapper converts the encoded signal to symbol values based on a modulation scheme. Finally, a modulator modulates the carrier light based on the symbol stream to generate the optical signal.
17. The transmitter of claim 16 , wherein the constellation mapper is programmable.
The optical transmitter that converts an N-bit input vector into an M-bit data stream using a tree code mapping, applies FEC, converts the encoded signal to symbols, and modulates a carrier light, includes a programmable constellation mapper. The constellation mapper's programmability allows for dynamic alteration of the modulation scheme.
18. The transmitter of claim 16 , further comprising: a controller configured to receive a parameter indicative of a data transmission performance of the optical communications system and to adjust the first mapping to tune the data transmission performance of the optical communications system, wherein the controller is configured to adjust the first mapping by: decreasing the number of data bits per baud of the optical signal if the parameter is greater than a first predetermined threshold; and increasing the number of data bits per baud of the optical signal if the parameter is less than a second predetermined threshold.
The optical transmitter that converts an N-bit input vector into an M-bit data stream using a tree code mapping, applies FEC, converts the encoded signal to symbols, and modulates a carrier light, also includes a controller. This controller monitors the optical communication system's data transmission performance. Based on a received parameter, the controller adjusts the N-bit to M-bit mapping. If the parameter is greater than a specified threshold, the number of data bits per baud is decreased. If the parameter is less than a specified threshold, the number of data bits per baud is increased.
19. The transmitter of claim 18 , wherein the controller is configured to adjust at least the first mapping by any one or more of: adjusting a number of data bits per baud of the optical signal; adjusting a ratio between N and M; adjusting a number of 0's in the M-bit data stream; and applying respective different probability distributions to at least two bits of each symbol of the symbol stream.
In the adaptive optical transmitter that converts an N-bit input vector into an M-bit data stream using a tree code mapping, applies FEC, converts the encoded signal to symbols, modulates a carrier light, and includes a controller for adjusting the initial mapping based on performance, the controller adjusts the initial mapping by modifying one or more of the following: the number of data bits per baud, the ratio of N to M, the number of zeros in the M-bit data stream, or the probability distributions applied to individual bits within each symbol.
20. The transmitter of claim 18 , wherein the first mapping comprises any one or more of a shaping function and a shell coding.
In the optical transmitter that converts an N-bit input vector into an M-bit data stream using a tree code mapping, applies FEC, converts the encoded signal to symbols, modulates a carrier light, and includes a controller for adjusting the initial mapping based on performance, the N-bit to M-bit mapping utilizes shaping functions and/or shell coding techniques. These techniques are used to optimize the signal constellation for better performance.
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June 13, 2013
July 4, 2017
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